Method and means for forming sheets from pulp



Feb. 21, 1933. w. J. HYDE 1,898,372

METHOD AND MEANS FOR FORMING SHEETS FROM PULP Filed March 18. 1931 2 Sheets-Sheet 1 Feb. 21,, 1933. w DE 1,898,372

METHOD AND MEANS FORFORHING SHEETS FROM PULP Filed March 18. 1931 2 Sheets-Sheet 2 g 1 m 1 m i1 i1 14 Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE WILLIAM J. HYDE, OF CLOQUET, MINNESOTA, ASSIGNOR TO THE NORTHWEST PAPER COMPANY, OF OLOQUET, MINNESOTA, A CORPORATION OF MINNESOTA METHOD AND MEANS FOR FORMING SHEETS FROM PULP Application filed March 18, 1931. Serial No. 523,410.

The present invention relates to papermaking and machines therefor, and has particular reference to a construction ofthe floor in the outflow chamber of the head box,

comes up on a roll from the lower stretch,

of its endless loop. Above the apron there is usually a lip which is vertically adjustable to regulate the width of the discharge slot from which the sheet-like stream flows.

' Rearwardly of the slot there may be an agitating device, such as a highly perforated revolving cylinder with large holes, say one inch in diameter, through which the outflowing suspension must pass. The pulp streams forth overthe apron very rapidly and frequently in localized streams which cause streaks on the underside of the paper sheet. The sheet-stream is not uniform under these conditions of operation. Certain combinations of conditions result in non-uniform streaming, apparently making localized streams of high and low concentration, or other undesired conditions of non-homogeniety, such as uneven speeds of'flow at var1ous places in the stream. These register.

in the sheet as streaks of varying formation and are undesirable.

hill-like obstruction in the apron over which the suspension must stream.

Another object is the provision of an adjustable mechanism whereby the character of the hill-like obstruction may be varied according to the necessities ofprevailing conditions.

Various other objects and advantages of the invention will become apparent from the following description of several exemplary.

embodiments of the invention shown in the accompanying drawings, in which:

Fig. 1 is a cross-section of a portion of a paper machine showing parts used in connection with the present invention, and is a view taken on line'11 of Fig. 3.

Fig. 2 is a similar view of another the invention.

Fig. 3 is a front view of the parts shown in Fig. 1.

Fig. 4 is a front view of a modified form of the invention having an adjustable element therein,-sl 1owing a portion in cross-section on the line 4-4 of Fig. 5.

Fig. 5 is a cross-section like Figs. 1 and 2 of the form shown in Fig. 4 taken on line 5-5 of Fig. 4.

. In the drawings an endless wire screen having upper stretch 10 passes over a breast form of 'roll 11. A deckel strap 12,-such as an endless strap of rubber, passes over idler pulley A 13, and has a lower stretch 14 running on the wire screen near the margin thereof in the usual manner to fence off the edges and retain the liquid on the screen. Rearwardly of the breast roll there is the usual head box 15 in which a constant level of pulp pensionmay be maintained. The floor of the head box projects as a ledge, or apron board 16, toward the breast roll 11. The head box has a front wall 17 from which projects with a downward slope a lip board 18 pivotally mounted on the axis designated 19. It terminates just above the top of the breast roll forming an elongated slot 20 from which streams a sheet of pulp suspension. The lip board is suitably adjustable to vary the width of. the slot, by mechanism not shown,

a ndis locally adjustable to provide uniformity to the sheet or slot by the adjusting rods 21. Side walls 22 close the ends of the space between the lip and apron boards forming an outlet chamber 23. Inside the head box in front of the outlet chamber 23 there is a rotary hollow perforated cylinder 24, with large holes for ermitting passage of pulp suspension and or agitating it, breaking it up and producing'unlformity of concentratlon. Secured to the apron board is an apron suchas a sheet of flexible rubberized fabric 25, in part defining the slot 20 and, if desired, projecting beyond the slot onto the. moving wire 10. The apron closes the gap between the head box 15 and the wire 10 and provides the surface on which the pulp suspen sion flows from the head box onto the wire. The foregoing description is exemplary of usual constructions in such machines.

The present invention relates to the apron on the floor in the outflow chamber over which the pulp suspension flows. Heretofore, the apron surface has been substantially plane from the wire edge of the apron back into the head'box. This has permitted the liquid to flow unimpeded on the apron, and has caused or permitted the localized streaming which produces the undesired streaks. I have discovered that if an obstacle is placed inthe path of the streaming liquid the localized streams are broken up,-

andthat the liquid suspension acquires uniformity which it maintains in the remainder of its flow to the wire.

Several forms of obstacles are possible and the. particular type which is preferred will depend upon the machine construction on which it is embodied, the kind of paper to be made,-the speed of operation, and the similar factors of influential character.

I prefer to maintain the apron surface as a continuous and unbroken surface directly to the wire in' the manner heretofore employedfand hence illustrate the invention as I have applied it in pa er machines equipped with a-rubber apron or such constructions.

' But it will be understoo that various modifications and changes an otherembodiments of the invention may be made without departing from the spirit and scope'of the invention as expressed in the appended claims.

In Fig. 1- the apron board 16 is located below the level of'the wire, and the apron 25 is carried upwardly as a rounded hill obstruction to reach the level of the wire. I refer to support the apron to form the hill y contact directly on the moving wire passin over the breast roll.

this form any localized pulp streams travelling directly'on the apron meet the hill at high velocity. and are deflected upwardly into the movingstream above. Thus, .the localizedstreams are broken up and the liquid suspension made 'more uniform. "-Newly localized streams do not form thereafter as there is insufiicient length of time and 'of travel to permit it.

In Fig. 2 I represent a machine in which .and is deflected upwardly causing irregular or non-streaming flow from that point onward. From the obstruction to the outletslot 20 there is insuflicient time and travel for a new formation of localized streams. The slot discharge is therefore suitably uniform in character. 1

The form of Fig. 1 is made practically permanent in constructing the machine. The form of Fig. 2 may be varied by changing the size or form of the bar 28. A triangular bar may be used or other shapes, but the round form shown is satisfactory and effective, and is preferred. In ordinary machines the bar 28 may not be inserted or changed while the machine is in operation.

In the form shown in Fig. 5 I provide an adjustable obstruction which may be changed without a replacement operation while the machine is in operation. In the apron board 30 there is provided a recess 31 in which there is an obstructing hill-forming member underlying apron 32. The obstructing member is movable vertically in the recess to vary the height of the hill formed by it in the apron. I prefer to employ a roundform, as in Fig. 2. A suitable construction is illustrated in which a rounded bar, such as a circular bar 33, is

.eccentrically mounted on rigid or integral pins or trunnions 34. These act as bearings in side plates35 (Fig. 4) One or both of the trunnions may project to the outside and at the end be provided with means for turning the bar 'such as a square head 36. A portion of the bearing shank may be threaded to carry a locking nut 37 Any other locking means j may be provided. By this construction the hill in the apron may be varied in height as conditions may require. The eccentricity may be arranged so that the hill is practically eliminated if desired.

The present invention therefore provides apparatus which causes an improved formation of a paper sheet. It provides an improved method of discharging pulp suspen sion onto a wire.

Because of the tapered form of the outlet chamber, the liquid stream is narrowed down and it acquires an increasing velocity as it approaches the slot 20. The layer in contact with the floor, or apron, drags slightly or is retarded by friction. Any slight irregularities in the apron may readily increase the lag and thus produce localized streaming. The obstruction of the present invention in effect lifts the retarded layer from the floor. causes it to mix with the upper layers, and this forces formation of a new layer on the floor on the slot side of the obstruction. At this point the speed is much greater than at points nearer the head box. The increased speed and shorter distance to be travelled together prevent the further formation of undesirable localized streaming. In the form of Fig. 1 mixing occurs nearer to the slot than in the other forms, but in each instance the deflection takes place in the confined stream, and irrespective of that, it occurs sufficiently close to the discharge slot so that new localized streams may not form to an undesirable, extent.

I claim:

1. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen'positioned to receive a discharge from'said slot, an apron on the floor of said outflow chamber in part defining said slot and terminating over said screen, and means forming a hill-like obstruction in said apron. I v 2. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen positioned to receive a discharge from said slot, and a floor in sa d chamber extending toward said screen and in part defining said slot. said floor having a rising obstruction therein.

3. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen positioned to receive a discharge from said slot. said screen having its receiving level slightly above'the level of the bottom of said outflow chamber, a roll over which said screen passes, and aflexible sheet or apron extending from said floor and in part defining said slot, said apron being supported by the screen on the roll to form a rising incline in the outlet chamber rear-- wardly of the slot.

4. In a paper making machine, means for discharging pulp onto a screen comprising in combination. an endless screen. a breast roll said floor upwardly around the 'breast roll at least to the edge of said lip board at the lower part of saidslot.

5. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, ail-endless movable screen, positioned to receive a discharge from said slot, a flexible sheet or apron on the floorof said chamber extending to the wire and in part defining said slot, and an elongated bar positioned on the floor and under said member to form a hill-like obstruction in the apron.

6. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen positioned to receive a disless movable screen positioned to receive adischarge from said slot, a flexible sheet or apron mounted to provide the bottom surface of said outlet chamber, said apron extending to the wire and in part defining said slot, and a fixedly mounted elongated member under said apron forming a hill-like obstruction in said apron surface.

8. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen positioned to receive a discharge from said slot, a flexible sheet or apron mounted to provide the bottom surface of said outlet chamber substantially level with the screen, said apron extending to the wire and in part defining said slot, and a fixedly mounted elongated member under said apron forming a hill-like obstruction in said apron surface.

9.- In a paper making'machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen vpositioned to receive a discharge from said slot, a flexible sheet or apron mounted to provide the bottom surface of said outlet chamber, a supporting floor under said apron having a gap therein, and an elongated element verticallyadjustable in said gap to lift said apron and form therein a hilllike obstruction.

10. In a paper making machine having an outflow chamber with a discharge slot for a pulp suspension, in combination, an endless movable screen positioned to receive a discharge from said slot, a flex ble sheet or apron mounted to provide the bottom surface of said outlet chamber, a supporting floor under said apron having a gap therein, and a rotatable, round-form elongated bar eccentrically mounted in said gap for forming a hill-like obstruction of variable height in said apron.

11. An outflow chamber between the head of a discharge slot, and a hill-like obstruction v box and wire of a paper machine comprising in combination, side walls, a lip board at the top, a floor at the bottom, said lip board and floor converging to form a slot between them, said floor being generally at a level below the slot and having a hill-like rise to the level of the slot.

12. An outflow chamber between the head box and wire of a paper machine comprising in combination, side walls, a lip board at the top, a floor at the bottom, said lip board and floor converging to form a slot between them, said floor being generally at the level of the slot, and a hill-like obstruction in said floor rearwardly of said slot.

- 13. In a paper making machine having an outflow chamber for discharging a pulp suspension onto a moving wire, means providing a continuous surface and forming a floor in said chamber and also forming one edge of a discharge slot, and a rising obstruction in said floor.

14. In a pa er making machine having an .tflow cham r for discharging a pulp suspension onto a moving wire, means providmg a continuous surface and forming a floor 1n sa1d chamber and also forming one edge in said floor.

15. In a pa er making machine having an outflow cham r for discharging a pulp suspension onto a moving wire, means providing a continuous surface and forming a floor in said chamber at a substantially constant level and also forming one edge of a discharge slot, and a small hill-like obstruction formed in said otherwise level floor.

16. In a paper making machine having an outflow chamber for discharging a pulp suspension onto a moving wire, means providlng a continuous surface and forming a floor in said chamber and also forming one edge of a discharge slot, a rising obstruction in sa1d floor, and on the other side of the obstruction a drop in the level of the floor.

ly into the upper part of said stream.

19. The method of dischar ing a pulp suspension from a supply thereo onto a moving screen for the formation of a sheet which comprises, flowing the suspension in a stream on a floor onto the screen, and deflecting the layer of suspension adjacent the floor upwardly into the upper layers of the stream prior to discharge onto the screen.

20. In a paper making machine having an outflow box for discharging a pulp suspension onto a moving wire, means providing a floor over which the pulp suspension streams at high velocity to flow onto said Wire, and an.obstruction in'the path of the layer of suspension on said floor positioned to deflect said moving layer upwardly and into upper layers of said suspension to mix therewith.

In testimony whereof I have hereunto affixed my signature.

- WILLIAM J. HYDE.

11., The method of discharging a pulp suspension from a supply thereof onto a moving screen for the formation of paper which comprises flowing a confined stream of said suspension between confining walls including a floor to discharge a sheet-like stream, and

deflecting upwardly the layer of suspension which follows said floor, said deflection being made at a time and place in the floor just prior to discharge of the sheet, and within the region of the confined stream.

18. The method of discharging a pulp suspension from a supply thereof onto a moving screen for the formation of paper which comprises flowing a stream of pulp suspension into a confinmg chamber, narrowing down the confined stream by the structure .of the chamber to form a sheet discharge through a slot in the chamber, and prior to discharge of the stream through said slot deflecting the 4 

